grok_intmath.h

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/*
 *    Copyright (C) 2016-2020 Grok Image Compression Inc.
 *
 *    This source code is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This source code is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 *    This source code incorporates work covered by the BSD 2-clause license.
 *    Please see the LICENSE file in the root directory for details.
 *
 */
 
#pragma once
 
namespace grk {
 
static inline uint32_t uint_subs(uint32_t a, uint32_t b)
{
    return (a >= b) ? a - b : 0;
}
 
static inline uint32_t uint_adds(uint32_t a, uint32_t b) {
        uint64_t sum = (uint64_t) a + (uint64_t) b;
        return (uint32_t)(-(int32_t)(sum >> 32)) | (uint32_t) sum;
}
 
template<typename T> uint32_t ceildiv(T a, T b) {
        assert(b);
        return (uint32_t)((a + (uint64_t) b - 1) / b);
}
 
template<typename T> T ceildivpow2(T a, uint32_t b) {
        return (T)((a + ((uint64_t) 1 << b) - 1) >> b);
}
 
static inline uint32_t uint64_ceildivpow2(uint64_t a, uint32_t b) {
        return (uint32_t)((a + ((uint64_t) 1 << b) - 1) >> b);
}
 
static inline uint32_t uint_floordivpow2(uint32_t a, uint32_t b) {
        return a >> b;
}
template<typename T> T floorlog2(uint32_t a) {
        T l;
        for (l = 0; a > 1; l++) {
                a >>= 1;
        }
        return l;
}
 
static inline int32_t int_fix_mul(int32_t a, int32_t b) {
#if defined(_MSC_VER) && (_MSC_VER >= 1400) && !defined(__INTEL_COMPILER) && defined(_M_IX86)
    int64_t temp = __emul(a, b);
#else
        int64_t temp = (int64_t) a * (int64_t) b;
#endif
        temp += 4096;   //round by adding "0.5" in 13-bit fixed point
        assert((temp >> 13) <= (int64_t) 0x7FFFFFFF);
        assert((temp >> 13) >= (-(int64_t) 0x7FFFFFFF - (int64_t) 1));
 
        // return to N-bit precision
        return (int32_t)(temp >> 13);
}
}